1. Field of the Invention
This invention relates generally to tape cassettes, and more particularly is directed to improvements in a tape cassette for preventing entwining of the tape with a guide structure which determines the path of tape movement within the cassette housing.
2. Description of the Prior Art
In a conventional compact tape cassette, for example, of the type CP-II, which satisfies EIA standard RS-399A, a substantially flat, rectangular housing has supply and take-up reels or winding cores rotatably disposed therein in side-by-side relation, and a magnetic tape is secured at its ends to the cores and is wound thereon to provide coils of the tape on the respective cores, with the tape between such coils being guided in a path having a portion extending along or parallel to the front side of the cassette housing. Such front side of the housing is formed with a number of openings so that, when the cassette is operatively positioned in a suitable magnetic tape recording and/or reproducing apparatus, in which position winding spindles extend through apertures in the bottom wall of the cassette housing and engage the winding cores, while a recording/reproducing head can reach through one of the openings in the front side of the cassette housing for engagement with the tape therebehind and a pressure roller can extend through another of the openings in the front side of the housing for pressing the tape against a capstan which projects upwardly into the cassette housing and is rotated for driving or transporting the tape when the latter is pressed thereagainst by the pressure roller. In a conventional compact tape cassette, the guiding means for determining the path of the tape between the coils thereof on the supply and take-up reels or cores includes guide rollers disposed within the housing adjacent the opposite ends of the front side of the housing, and being engaged by the tape at the sides of the guide rollers facing away from the adjacent coils. Furthermore, in most existing conventional compact tape cassettes, a guide pin is disposed within the cassette housing adjacent each guide roller for engagement with the tape of a location along the latter between the respective guide roller and the adjacent coil, and a bracket guide is provided within the cassette housing in back of each of the front openings thereof which is intended to receive a pressure roller so that each bracket guide can ensure proper engagement of the tape by the pressure roller and capstan.
In a compact tape cassette, as aforesaid, the turns of tape making up each of the coils may become loosened due to uncontrolled turning of the reels or cores, particularly when the cassette is not in use. When a tape coil becomes loosened in a conventional compact tape cassette, the driving of the tape, for example, as by the cooperative action of a pressure roller and capstan in a magnetic tape recording and/or reproducing apparatus in the direction to unwind the tape from the loosened coil can result in so-called "tape entwining", that is, the tape becomes entwined or wrapped around the guiding means therefor adjacent the loosened coil. When such tape entwining occurs, further transportation of the tape is blocked and, if the driving of the tape by the pressure roller and capstan is not discontinued immediately upon the developement of excessive resistance to transportation of the tape, the tape may break or, at least, the recording and reproducing characteristics of the tape will be seriously deteriorated. Thus, tape entwining has been a serious problem in conventional compact tape cassettes.